I'm under the impression they get at least some input in choosing their own WWE name. As long as he gets to keep a mask and the gimmick isn't altered negatively, whatever name he goes with will be fine. If you use Cesaro and Ohno as examples, I'm sure his overall gimmick will be fine as it should. I do think they will focus on him being from Montreal as opposed to Mexico though. Ole!
The reason why we don't get new fresh ideas and promotions rising in Pro Wrestling is because the majority of the community is happy with the same old shit and will reject any chance of change. There is a risk in doing new things, 9/10 that leads of 50+ pages of bitching and moaning.